In Greek mythology, Atreus was a king of Mycenae, son of Pelops and Hippodamia, and father of Agamemnon and Menelaus; his descendants are the Atreidae. Exiled with his brother Thyestes for the murder of their half-brother Chrysippus, he became ruler of Mycenae and entered a feud with Thyestes over the golden lamb, adultery, and a banquet of Thyestes' own children — a cycle of vengeance that cursed the House of Atreus down to Orestes.
Adapted from Wikipedia, "Atreus" · CC BY-SA 4.0
I.Nomenclature
'Atreides' (Ἀτρείδης) is a patronymic form of Atreus which refers to one of his sons — Agamemnon or Menelaus. The plural forms Atreidai / Atreidae refer to both sons collectively, or to the more distant descendants of Atreus known as the House of Atreus. It has been suggested that the name Attarsiya, belonging to an Ahhiyawan king of about 1400 BC in Hittite records, may be a Hittite rendition of the Greek name.
II.Atreus and Thyestes
Atreus and Thyestes were exiled by Pelops for murdering their half-brother Chrysippus and took refuge in Mycenae, where they ascended the throne in the absence of Eurystheus. Atreus vowed to sacrifice his best lamb to Artemis but hid a golden lamb he found; his wife Aerope gave it to her lover Thyestes, who used it to claim the kingship. Atreus regained the throne after Zeus arranged a portent in which the sun reversed its course.
Learning of the adultery, Atreus killed Thyestes' sons, cooked them (save hands and feet), and tricked Thyestes into eating the flesh before revealing the truth. An oracle then advised Thyestes to father a son by his daughter Pelopia who would kill Atreus; that son, Aegisthus, was raised for a time by Atreus and eventually slew him. Before his death Atreus and Aerope had Agamemnon, Menelaus, and a daughter Anaxibia.
III.The House of Atreus
The curse on the house is traced back through Pelops — who won Hippodamia by Myrtilus's sabotage and was cursed by the dying charioteer — to Tantalus, who served Pelops's flesh to the gods. Agamemnon's sacrifice of Iphigenia, Clytemnestra's murder of Agamemnon with Aegisthus, and Orestes' revenge continue the cycle; Aeschylus's Oresteia presents Orestes' trial as the end of the inherited curse.
IV.Classical and Hittite references
Plato in The Statesman recalls the "famous tale" that the sun and stars once rose in the west and set in the east as testimony to Atreus's right. The Hittite "Indictment of Madduwatta" mentions a Greek leader Attarsiya; some scholars identify him with Atreus, while others argue that even if the name is related, the person need not be the famous mythic king.